Loans and Allowance for Losses - Schedule of Impaired Financing Receivables (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Impaired [Line Items]
Impaired loans, with no specific allowance, recorded investment	$ 52,191	$ 32,012
Impaired loans, with no specific allowance, unpaid principal balance	52,014	31,854
Impaired loan, with a specific allowance, recorded investment	174,385	123,300
Impaired loans, with a specific allowance, unpaid principal balance	173,844	122,786
Impaired loans, associated allowance	6,541	3,405
Recorded investment	226,576	155,312
Unpaid principal balance	225,858	154,640
Recorded investment of loans on nonaccrual status	87,781	61,408
Average recorded investment in impaired loans	190,106	152,777
Income recognized on impaired loans	2,753	3,446
Less than 90 days past due
Financing Receivable, Impaired [Line Items]
Recorded investment of loans on nonaccrual status	30,100	41,800
Crops
Financing Receivable, Impaired [Line Items]
Impaired loans, with no specific allowance, recorded investment	30,846	20,734
Impaired loans, with no specific allowance, unpaid principal balance	30,741	20,632
Impaired loan, with a specific allowance, recorded investment	84,044	59,335
Impaired loans, with a specific allowance, unpaid principal balance	83,772	59,098
Impaired loans, associated allowance	2,725	1,606
Recorded investment	114,890	80,069
Unpaid principal balance	114,513	79,730
Recorded investment of loans on nonaccrual status	34,037	26,611
Average recorded investment in impaired loans	101,053	74,804
Income recognized on impaired loans	1,157	1,219
Permanent Plantings
Financing Receivable, Impaired [Line Items]
Impaired loans, with no specific allowance, recorded investment	16,696	3,592
Impaired loans, with no specific allowance, unpaid principal balance	16,638	3,573
Impaired loan, with a specific allowance, recorded investment	36,852	38,176
Impaired loans, with a specific allowance, unpaid principal balance	36,732	38,009
Impaired loans, associated allowance	1,051	1,134
Recorded investment	53,548	41,768
Unpaid principal balance	53,370	41,582
Recorded investment of loans on nonaccrual status	22,849	21,349
Average recorded investment in impaired loans	44,986	44,461
Income recognized on impaired loans	625	1,687
Livestock
Financing Receivable, Impaired [Line Items]
Impaired loans, with no specific allowance, recorded investment	3,195	5,764
Impaired loans, with no specific allowance, unpaid principal balance	3,185	5,737
Impaired loan, with a specific allowance, recorded investment	47,113	19,443
Impaired loans, with a specific allowance, unpaid principal balance	46,984	19,361
Impaired loans, associated allowance	2,636	522
Recorded investment	50,308	25,207
Unpaid principal balance	50,169	25,098
Recorded investment of loans on nonaccrual status	28,441	8,803
Average recorded investment in impaired loans	36,054	24,523
Income recognized on impaired loans	687	299
Part-time Farm
Financing Receivable, Impaired [Line Items]
Impaired loans, with no specific allowance, recorded investment	1,398	1,922
Impaired loans, with no specific allowance, unpaid principal balance	1,394	1,912
Impaired loan, with a specific allowance, recorded investment	6,376	6,276
Impaired loans, with a specific allowance, unpaid principal balance	6,356	6,249
Impaired loans, associated allowance	129	142
Recorded investment	7,774	8,198
Unpaid principal balance	7,750	8,161
Recorded investment of loans on nonaccrual status	2,454	4,645
Average recorded investment in impaired loans	7,953	8,758
Income recognized on impaired loans	284	241
Ag. Storage and Processing
Financing Receivable, Impaired [Line Items]
Impaired loans, with no specific allowance, recorded investment	0	0
Impaired loans, with no specific allowance, unpaid principal balance	0	0
Impaired loan, with a specific allowance, recorded investment	0	0
Impaired loans, with a specific allowance, unpaid principal balance	0	0
Impaired loans, associated allowance	0	0
Recorded investment	0	0
Unpaid principal balance	0	0
Recorded investment of loans on nonaccrual status	0	0
Average recorded investment in impaired loans	0	0
Income recognized on impaired loans	0	0
Other
Financing Receivable, Impaired [Line Items]
Impaired loans, with no specific allowance, recorded investment	56	0
Impaired loans, with no specific allowance, unpaid principal balance	56	0
Impaired loan, with a specific allowance, recorded investment	0	70
Impaired loans, with a specific allowance, unpaid principal balance	0	69
Impaired loans, associated allowance	0	1
Recorded investment	56	70
Unpaid principal balance	56	69
Recorded investment of loans on nonaccrual status	0	0
Average recorded investment in impaired loans	60	231
Income recognized on impaired loans	0	0
Collateral Dependent Not Individually Analyzed
Financing Receivable, Impaired [Line Items]
Impaired loans, associated allowance	3,000	2,700
Recorded investment	$ 159,100	$ 120,900
Impaired loans, impairment analysis performed percent	70.00%	78.00%